[Region Refactoring] Refactor gdip_region_convert_from_path

[hughbe]

• Clear the region in gdip_region_create_from_path
• Add missing status checks in calls to GdipAddPathRectangle
• Explicitly handle RegionTypeInfinite in gdip_region_convert_to_path
• Implement gdip_region_convert_to_path on top of gdip_region_create_from_path
• Rename gdip_region_create_from_path to match meaning

This change achieves some things

• Adds missing status checks and memory leaks in the error path where GdipAddPathRectangle fails
• Avoid duplicate code (e.g. creating the path tree and clearing the existing path data) between gdip_region_convert_from_path and gdip_region_create_from_path
• Avoid duplicate code clearing the path data each time we call gdip_region_create_from_path: we should always clear existing data!
• Rename gdip_region_create_from_path to gdip_region_set_path to better match the meaning of the method - we're not actually creating a region, but rather overwriting existing data

The motivation for this is to avoid duplicate code and enable future refactorings such as lazily creating path tree data

Should be merged BEFORE #675

[hughbe]

Closing, as libgdiplus is deprecated